Images are visual content. For this information to become accessible to the blind or visually-impaired, there must be a conversion of a visual image into alternative sensory data. A conversion into some tactile form has been the most popular alternative.
Tactile literacy is critical to enhance the social and physical capabilities of people who are blind, to help them pursue higher levels of education in Science, Technology, Engineering, and Mathematics (STEM) fields and other areas of post-secondary education that require basic STEM literacy, and ultimately obtain professional level employment in STEM fields or other professional disciplines.
There are numerous prior studies related to the task of making visual information accessible in tactile forms for the blind population. To date, research on haptic object processing has dealt almost exclusively with inanimate objects. Many of the early studies in this field during the 1960s and 1970s addressed the processing of geometric properties, particularly their shape and size, using the haptic and visual systems. The haptic system performed quite poorly in those studies. More recent studies have investigated how well blind-folded sighted, visually-impaired, and blind observers can identify common objects at the basic level, as depicted in raised-line drawings. Accuracy has varied from very poor in open-set identification to very good with small closed sets and/or when observers were initially primed with the superordinate category represented by the drawing. Corresponding mean response times, however, have been consistently high—for example, ranging from 30 to 71 seconds across various conditions in one study, and 90 seconds or more in other experiments.
In contrast—Tadoma—a method used by deaf-blind individuals to understand spoken speech by statically contacting faces in real time, serves as an existence proof that the haptic system can process complex information both accurately and quickly. Reports have documented highly efficient haptic performance. They required blind-folded participants to haptically explore and identify an open set of 100 common 3-D objects as quickly and as accurately as possible. Naming accuracy was 99%, and the modal response time was only about 2 seconds, indicating excellent processing efficiency by the haptic system in terms of high accuracy combined with high speed.
However, unlike in the case of Braille text for which commercially available devices such as Braille-Note BT32 personal organizer have been widely used, the abovementioned studies have not converged to any widely adopted haptic system or technique. Currently, various types of tactile graphics are used in rendering images. Popular ways of doing this in existing practice include those relying on tactile embossers, swell paper, or thermoform. Tactile embossers such as the Tiger printers from ViewPlus (www.viewplus.com) render graphics by raised-lines that are formed by the striking pins of the printer. Swell-paper-based rendering utilizes heat sensitivity of microcapsules in the paper to create a raised-ink image. Thermoform uses a technique of molding plastic into a matrix, forming a relief model with a vacuum press and high temperature.
Even though various types of tactile graphics techniques are currently commonplace, a wide range of challenges remains to be addressed. First, the techniques described above have only limited resolution and relief variation. This in turn requires an image to be heavily simplified—and often re-created—before it can be rendered. In the existing practice, this process is largely done manually by sighted transcribers on an ad hoc, per-image basis. Since the images in STEM classes are so diverse, it remains a challenge to establish proper procedures for this critical step in the tactile rendering of an image.
Second, the use of tactile images requires that the user learn how to interpret this format, especially when the task is to learn something that cannot be easily conveyed by words. Although the visually-impaired regularly interact with tactile surfaces, their focus has not been towards interpreting image information. This presents a new challenge in developing a successful tool for the blind, because it is not known what the appropriate format is of the specific details that are distinct and easily identifiable in the image. Furthermore, those who use touch to perceive their environment do so by feeling the shape, surface and size of an object. This perception is not the same as being able to interpret what an object represents. As with any image, it is always harder to identify something that the student have little or no prior experience with, which is another consideration when determining how well a tactile image is being interpreted.
Third, images are in general a two-dimensional (2D) representation of a three-dimensional (3D) object. Those who are visually-impaired, especially from an early age, have limited perception of image depth, because they have not had the development of spatial relationships like those who can see. Thus, the ability to interpret a given 3D tactile image in its context may vary from one individual to another, depending on factors like the degree of exposure to such medium in the past, whether the individual had sight before, etc. This suggests that an optimal solution may need to be person-adaptive, which is a challenge that has not been addressed in the existing practice. While there are some known parameters that have been determined in the literature regarding proper tactile rendering, one can recognize the many remaining challenges that have been identified above.
Therefore, there is a need to overcome these challenges, by providing assistance to blind or visually-impaired students, and by developing new tools and methodologies that will allow them to sense and “visualize” 3D images. This would help remove one of the obstacles encountered by students that is preventing them from enrolling into vision-based classes or pursuing a career in STEM. The development of improved technology requires that one thoroughly evaluate the current tools, develop and optimize new tools, and understand what is needed to create an interpretable tactile image as well as collect information on how visually-impaired or blind students best learn how to utilize these tools.